Apparatus for manufacturing instant dry ice

ABSTRACT

Dry ice is produced by using the internal energy stored in a pressurized CO 2  tank or cylinder, which is usually between 300 to 350 PSI, to compress CO 2  snow. This same internal energy works whether using a low-pressure refrigerated tank of 300 to 350 PSI CO 2 , or a high-pressure tank of 800 to 900 PSI CO 2 , as controlled by a pressure safety valve, to compress the CO 2  snow. No other form of mechanical energy is required to make the solidified dry ice.

This application is a non-provisional application based upon provisional application Ser. No. 60/798,735, filed May 9, 2006, herein incorporated in its entirety by reference.

FIELD OF THE INVENTION

The present invention relates to the production of dry ice using pressure supplied from a pressurized liquid carbon dioxide storage tank.

BACKGROUND OF THE INVENTION

The history of making dry ice from carbon dioxide (CO₂) liquid is a slow and costly manufacturing process. First, liquid CO₂ is released into a chamber that collects CO₂ snow. The chamber is compressed by use of a hydraulic ram or other mechanism to compact the CO₂ snow. The energy that is used for compression is usually in the form of electric, gas or diesel motor energy.

While CO₂ snow is being formed, in most cases, vast amounts of CO₂ gas is allowed to dissipate into the atmosphere. The snow is then hydraulically compressed and/or extruded, in some cases both, to make solidified dry ice.

This is a slow and costly process because a start up time is required to begin the production of CO₂. CO₂ machines can cost upwards of $60,000 per machine. Additionally, to make one pound of dry ice requires approximately three pounds of CO₂ liquid. Hence the manufacturing cost is high.

SUMMARY OF THE INVENTION

The present invention makes the production cost of dry ice much less expensive in three ways. 1) A greater amount of dry ice per pound of liquid CO₂ is produced. 2) The invention produces dry ice without the cost or need for any mechanical energy. 3) The CO₂ chamber is far less costly to produce than most all other machines on the market.

This invention is a new and novel way of producing solidified CO₂ in the form of a block or cylinder of dry ice. The uniqueness of the invention is that it uses the internal energy stored in a pressurized CO₂ tank or cylinder, which is usually between 300 to 900 PSI, to compress CO₂ snow. This same internal energy works whether using a low-pressure refrigerated tank of 300 to 350 PSI CO₂, or a high-pressure tank of 800 to 900 PSI CO₂, to compress the CO₂ snow. No other form of mechanical energy is required to make the solidified dry ice.

The invention allows for the compression of blocks or cylinders of dry ice weighing several pounds to be made in a very short period of time. A feeder line (hose) from a liquid CO₂ source, with a safety valve on the end of the line is connected to the chamber of the invention.

End caps connected to opposite ends of the chamber can be screwed on, clamped on or attached by any other mechanical means of interlocking. The leading end cap includes a very small orifice, which allows controlled release of the CO₂ liquid into the chamber so that CO₂ reaches its triple point—gas, liquid and solid phases—based upon the pressure present in the chamber as the liquified CO₂ enters the chamber. The safety valve, connected to the leading end cap, controls the amount of pressure allowed to build up in the chamber.

The diameter of the opening of the orifice of the leading end cap is approximately 0.050 of an inch (fifty thousands of an inch). However, the diameter of the orifice will vary depending on the size of the chamber to be filled and the diameter and number of the holes in the chamber in order to maintain the proper pressure and flow rate to create CO₂ snow within the chamber.

The pressure inside the chamber, when it is being filled with solid CO₂ snow initially ranges between 20 to 75 PSI. As additional liquid CO₂ is fed into the chamber, the pressure rapidly increases to the pressure allowed into the chamber by the safety valve. The safety valve preferably allows entry of a pressure between 300 to 350 PSI. Above this pressure, the safety valve can open and release any excess pressure. When using low pressure CO₂ tanks the safety valve may not open, as the pressure does not reach a critical level.

This rapid increase in pressure, within the chamber, is due to the holes in the walls of the chamber becoming plugged with solid CO₂ snow. When the holes become plugged, the ability of the CO₂ gas to escape is greatly reduced. The expanding gas, in turn causes the trapped CO₂ snow to experience a tremendous amount of internal compression. The result is a uniform block of dry ice with a density of approximately 70 pounds per cubic foot—2472 pounds per cubic meter.

One example of a compression chamber is a cylindrical chamber made of aluminum of 30 cubic inches which has approximately 256 holes. This allows for the pressure to build up in the chamber which in turn quickly produces one pound of dry ice.

The chamber can be made of any material that can withstand an internal pressure higher than that of the safety release valve setting. The chamber can be round, square, triangular or any shape one chooses. The chamber can be of any size providing the CO₂ storage cylinder can supply enough pressurized liquid CO₂. The release end of the chamber can be a simple screw on cap or a sophisticated mechanical opening and closing of the chamber by a gate, as long as the cap is capable of containing the CO₂ snow.

By using a gate at the trailing end, an extrusion of solid CO₂ is permitted. It is even possible to produce a continuous processing of solid CO₂ through the trailing end, once solid CO₂ is initially formed. The pressure at the leading end will continuously push solid CO₂ out of the trailing end until the gate is closed or the liquid CO₂ tank is emptied, causing a rapid reduction in the pressure of the chamber.

The chamber of the invention has a series of minute holes throughout the walls of the chamber in an arranged symmetrical pattern. These holes are equally divided in all areas of the chamber along X, Y and Z axes. The holes are drilled or punched through the thickness of the chamber wall. The sizes of these holes are approximately 0.018 (eighteen thousands) of an inch in diameter. On different size chambers, however, the size of the orifice into the chamber and the size of the holes in the chamber walls will vary. The number of holes can range from 50 to 1000 or more.

The positioning of the holes is very important. Each hole is positioned in an alternating, uniform pattern that allows for an even distribution of CO₂ snow throughout the chamber. The pattern will vary depending on the shape of the chamber.

The factor that determines the sizes of the orifice and the holes is the ability to increase pressure within the chamber as the chamber is being filled. Once the chamber is filled, the pressure continues to increase due to the plugging of the holes, up to the pressure permitted by the safety valve. If the holes are too large, the snow under pressure will exit the chamber without gradual plugging up of the holes.

The entrapped pressure within the chamber acts as a ram compressing the snow into a solid piece of dry ice. When the CO₂ liquid is initially released into the chamber by opening the valve of the feeder line, the CO₂ liquid from the CO₂ tank is forced through the small orifice in the inlet cap. The pressure of the CO₂ storage tank propels the liquid CO₂ through the orifice leading into the chamber.

At this point, upon the entrance into the chamber, the liquid CO₂ passes through its triple point. First CO₂ gas and solid CO₂ snow begin filling the chamber. The pressure inside the tube is raised to between 20 to 75 PSI. As the pressure inside the chamber builds, the CO₂ gas and atmosphere in the chamber, seeking release, escapes through the minute holes. In a matter of seconds the holes begin to plug up in succession from the trailing end of the chamber by the CO₂ snow and gas which is being driven from the pressure within the CO₂ storage tank.

When the holes are plugged there is no additional escape route for the gas. This along with the pressure from the CO₂ tank and the build up of the pressure within the chamber causes tremendous compression of the CO₂ snow to take place inside of the chamber.

When the CO₂ snow is compressed, the triple point conditions cease to exist and only liquid CO₂ continues to fill the remaining void in the chamber. Once the valve to the liquid CO₂ storage tank is closed the additional build up of the internal pressure within the chamber by the expansion of liquid CO₂ to CO₂ gas forces enough snow and remaining gas out of the minute holes, allowing the remaining liquid to be further compressed and solidified.

An additional benefit is derived by the increase in CO₂ snow volume due to minimizing the amount of CO₂ gas that is allowed to escape from the chamber. This results in a higher volume of solid CO₂ than that of a conventional machine that produces dry ice.

Once the remaining compressed energy entrapped within the chamber dissipates, the dry ice can be removed. If one chooses to propel the solidified dry ice from the chamber for any reason such as the use in fire fighting, pollution control, etc. one of the end caps must be quickly released while there is still residual pressure inside the chamber. This will cause the encased dry ice to be propelled rapidly from the outlet end.

Accordingly, it is an object of the present invention to quickly produce solid CO₂ by a compression force from stored liquid CO₂.

It is another object of the present invention to quickly produce solid CO₂ by a compression force from stored liquid CO₂ in a chamber having minute holes which quickly are plugged by solid CO₂ to increase the pressure within the chamber and compact solid forming CO₂ by the pressure from the storage tank.

It is still yet another object of the present invention to quickly produce solid CO₂ by a compression force from stored liquid CO₂ by the introduction of pressurized liquid CO₂ in a chamber having minute holes which quickly are plugged by solid CO₂ to increase the pressure within the chamber and compact solid forming CO₂ by the pressure from the storage tank and to form a block of solid CO₂ having a density of approximately 70 pounds per cubic foot.

These and other objects of the invention, as well as many of the intended advantages thereof, will become more readily apparent when reference is made to the following description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings illustrate examples of various components of the Apparatus of Manufacturing Instant Dry Ice. Other embodiments that are substantially similar can use other components that have a different appearance.

FIG. 1 is an exploded view of a chamber and end caps for production of solid CO₂.

FIG. 2 schematically illustrates the feeding of stored liquid CO₂ through a safety valve into a compression chamber.

FIG. 3 illustrates the expansion of liquid CO₂ into CO₂ gas and compression into a solid upon introduction into the chamber.

FIG. 4 illustrates the filling of minute holes in the sidewalls of the chamber by solid CO₂ and continued introduction of liquid CO₂ into the chamber.

FIG. 5 illustrates the formation of a solid block of CO₂ within the chamber.

FIG. 6 illustrates the removal of the end caps from the chamber.

FIG. 7 illustrates the removal of a block of solid CO₂ from the chamber.

FIG. 8 illustrates the finished product of a block of solid CO₂.

FIG. 9 illustrates an alternate embodiment having a chamber tapered at one end and a movable gate controlling extrusion of solid CO₂ from the chamber.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In describing a preferred embodiment of the invention illustrated in the drawings, specific terminology will be resorted to for the sake of clarity. However, the invention is not intended to be limited to the specific terms so selected, and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose.

With reference to the drawings, in general, and to FIGS. 1 and 2, in particular, the pressure apparatus embodying the teachings of the subject invention is generally designated as 10. With reference to its orientation in FIG. 1, the pressure chamber 12 includes threading 14, 16 at its opposite ends for a receipt of internally threaded end caps 18, 20, respectively. The pressure chamber has a diameter of two to three inches.

In the figures, the chamber 12 is shown being constructed of transparent material. This is for illustrative purposes and it is understood that in the actual preferred embodiment of the present invention, the chamber 12 may be constructed of aluminum or other materials able to withstand the force of pressure from a liquid CO₂ storage tank 21 as limited by safety valve 22.

As shown in FIG. 2, the storage tank 21 is controlled by a valve 24 to release liquid CO₂ through a feed line 26 to a valve 28. A safety valve 22 is interposed between valve 28 and end cap 18 to control the pressure of CO₂ fed into chamber 12 through end cap 18. Pressure relief or safety valve 22 allows release of pressurized CO₂ gas exceeding a predetermined pressure.

In FIGS. 3 through 8, the method of the present invention will be demonstrated. Initially, as shown in FIG. 2, valve 24 of liquid CO₂ storage tank 21 is open to allow release of liquid CO₂ through feed line 26 to valve 28. As shown in FIG. 3, upon opening of valve 28 by rotation of handle 30 in the direction of arrow 32, controlled release of liquid CO₂ is allowed to pass in the direction of arrow 34 until reaching pressure safety valve 22. Pressure below a preset threshold is allowed to pass valve 22 in the direction of arrow 36 into apparatus 10, including chamber 12.

Chamber 12 includes a plurality of holes or perforations 40 in the sidewall of the chamber. As the liquid CO₂ passes first into the gas phase within the chamber, and upon continued pressurization into the solid phase due to pressure buildup in the chamber, the CO₂ gas and solid are allowed to escape through the holes 40 until, as shown in FIG. 4, the solid CO₂ fills and ultimately blocks escape of additional gas through the holes 40. The pressure thereby continues to increase in chamber 12 and the force of continued introduction of liquid CO₂ further compresses the solid CO₂ until a block 42 of solid CO₂ is formed in the chamber 12 as shown in FIG. 5.

The valve 28 is then closed by rotating handle 30 in the direction of arrow 44. The end caps 18, 20 may then be removed from the chamber 12 as shown in FIG. 6.

The block of solid CO₂ may then be pushed from the chamber 12 in the direction of arrow 46 as shown in FIG. 7. As shown in FIG. 8, the block 42 may then be used for any purpose normally associated with dry ice, having been formed in a quick, less expensive manner than previously known.

In FIG. 9, an alternate embodiment is shown where the apparatus 50 is formed by chamber 52. At a trailing end 54 of the chamber 52, the diameter of the tube is decreased at an angle of 10°-20° and is devoid of holes. The tapered trailing end extends 1-1.5 inches along a length of the chamber 52.

A gate 56 is pivotally mounted at end 54 about a pivot point 58 and secured by latch 60 at an opposite end from the pivot point 58. Once formation of a solid block of CO₂ has been achieved, the gate 56 may be pivoted in the direction of arrow 62 to the position shown in dotted lines in FIG. 9. The continued pressure of liquid CO₂ passing into the chamber 52 through end cap 18 forces the solid block 64 of CO₂ through the end 54 of the chamber 52 in an extrusion process. Solid block 64 is moved in the direction of arrow 66 as shown in dotted lines.

Therefore, by continued pressure from the inlet end of the chamber 52, a continuous block 64 of solid CO₂ is forced through the outlet end 54. A slicing gate may also be used to cut off sections of the block 64 as it passes through the trailing end 54.

The foregoing description should be considered as illustrative only of the principles of the invention. Since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and, accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention. 

1. An apparatus for manufacturing dry ice, said apparatus comprising a chamber, said chamber being able to withstand a pressure of at least 300 psi, a feed line connected to the chamber for passing pressurized liquid carbon dioxide into the chamber, and a plurality of minute holes formed in the chamber for controlled release of pressure from an interior of the chamber.
 2. The apparatus for manufacturing dry ice as claimed in claim 1, wherein a size of said holes is small enough to be blocked by carbon dioxide in a solid phase as the solid carbon dioxide is forced from the chamber under pressure.
 3. The apparatus for manufacturing dry ice as claimed in claim 2, wherein a size of said holes is at least approximately 0.018 inches.
 4. The apparatus for manufacturing dry ice as claimed in claim 2, wherein said holes are symmetrically located in said chamber.
 5. The apparatus for manufacturing dry ice as claimed in claim 2, wherein a number of the holes is greater than
 50. 6. The apparatus for manufacturing dry ice as claimed in claim 1, wherein the chamber includes two ends, and each of the two ends is sealed by an end cap.
 7. The apparatus for manufacturing dry ice as claimed in claim 6, wherein an inlet end of the chamber has an inlet end cap as one of the two end caps and includes an orifice of approximately 0.050 inches.
 8. The apparatus for manufacturing dry ice as claimed in claim 1, wherein a safety valve in said feed line controls a pressure of liquid carbon dioxide passing into the chamber.
 9. The apparatus for manufacturing dry ice as claimed in claim 1, wherein a trailing end of said chamber is tapered inwardly.
 10. The apparatus for manufacturing dry ice as claimed in claim 9, wherein a movable gate is located at the trailing end of the chamber to open and close the chamber.
 11. An apparatus for manufacturing dry ice, said apparatus comprising a chamber, said chamber being able to withstand a pressure of at least 300 psi, a feed line connected to the chamber for passing pressurized liquid carbon dioxide into the chamber, and a plurality of minute holes symmetrically formed in the chamber for controlled release of pressure from an interior of the chamber.
 12. The apparatus for manufacturing dry ice as claimed in claim 11, wherein a size of said holes is small enough to be blocked by carbon dioxide in a solid phase as the solid carbon dioxide is forced from the chamber under pressure.
 13. The apparatus for manufacturing dry ice as claimed in claim 12, wherein a size of said holes is at least approximately 0.018 inches.
 14. The apparatus for manufacturing dry ice as claimed in claim 11, wherein a safety valve in said feed line controls a pressure of liquid carbon dioxide passing into the chamber.
 15. The apparatus for manufacturing dry ice as claimed in claim 14, wherein the safety valve allows a pressure of up to 300 psi to enter the chamber.
 16. The apparatus for manufacturing dry ice as claimed in claim 12, wherein a number of the holes is greater than
 50. 17. The apparatus for manufacturing dry ice as claimed in claim 11, wherein the chamber includes two ends, and each of the two ends is sealed by an end cap.
 18. The apparatus for manufacturing dry ice as claimed in claim 11, wherein a trailing end of said chamber is tapered inwardly.
 19. The apparatus for manufacturing dry ice as claimed in claim 17, wherein an inlet end of the chamber has an inlet end cap as one of the two end caps and includes an orifice of approximately 0.050 inches.
 20. The apparatus for manufacturing dry ice as claimed in claim 18, wherein a movable gate is located at the trailing end of the chamber to open and close the chamber. 